1. Field of the Invention
A closing assembly for a magneto-rheological damper.
2. Description of the Prior Art
Magneto-rheological (MR) dampers are increasingly used on vehicles to continuously control damping characteristics for proper ride and handling in all driving situations. Magneto-rheological fluid generally consists of a clear carrier or base fluid (e.g. polyalphaolefin) with suspended particles. When the particles are charged with a magnetic field, they line up and change the viscosity of the fluid, which in turn can be used to control damping forces.
The closing system or assembly of an MR damper generally incorporates a primary seal and bearing surface for the piston rod of the damper. Known closing assemblies use one primary seal and a dry anodized bearing surface and are therefore limited in the amount of side-load the damper can handle. Other known closing assemblies incorporate a wet bearing through the use of two seals and a porous stainless steel rod guide. The rod guide can filter out the particles from the MR fluid so that only the base clear fluid lubricates the bearing and primary seal. However, even closing assemblies which filter the MR particles are susceptible to increases in friction over time due to metallic particles contaminating the carrier fluid near the bearing and the seals. Additionally, the carrier fluid of the MR fluid may not possess the ideal lubricity for properly lubricating the seal and bearing. Therefore, there remains a need for improved MR damper closing assemblies which can better handle increased friction over long periods of damper use.